RESUMO
The low-pressure die casting (LPDC) process was experimentally and numerically studied to produce AlSi7Mg0.3 components such as steering knuckles. Steering knuckles are important safety components in the context of a vehicle's suspension system, serving as the mechanical interface that facilitates the articulation of the steering to control the front wheel's orientation, while simultaneously bearing the vertical load imposed by the vehicle's weight. This work focuses on the development of a numerical model in ProCAST®, replicating the production of the aforementioned part. The model analyses parameters such as the filling dynamics, solidification process, and presence of shrinkage porosities. For the purpose of evaluating the quality of the castings, six parts were produced and characterised, both mechanically (tensile and hardness tests) and microstructurally (porosity and optical microscopy analysis). When correlating simulation results with the available experimental data, it is possible to conclude that the usage of the LPDC process is a viable alternative to the use of steels and other metals for the production of very high-quality castings while using lighter alloys such as aluminium and magnesium in more demanding applications.
RESUMO
The effect of the application of a rotating magnetic field on the average grain size of IN718 castings was experimentally studied. For the purpose, four parts were produced by investment casting and characterized. The first casting was produced without application of RMF for comparison. The remaining ones were submitted to different RMF frequencies for 15 min and subsequently to the pouring of the nickel-based superalloy. In these three castings, the RMF frequencies applied were, respectively, 15 Hz, 75 Hz and 150 Hz. All the other process parameters were kept constant during the execution of the experimental procedure. The average grain size of the samples was determined according to the ASTM E112-13 standard, using intercept methods. Macro hardness measurements, tensile testing and SEM-EDS analysis were conducted in order to evaluate the casting's mechanical properties and microstructures. The results demonstrate a noticeable grain size reduction in the samples submitted to rotating magnetic field. An average grain area reduction, greater than 96%, was achieved in the castings where RMF frequencies of 75 Hz and 150 Hz were applied. The application of RMF also caused a morphological change in the casting's dendrites from cellular to almost equiaxed. Additionally, it originated the decrease of the size and amount of needle-like δ phase. Regarding mechanical properties of the cast parts, no major differences were verified.
RESUMO
Transition-metal sulfides combined with conductive carbon nanostructures are considered promising electrode materials for redox-based supercapacitors due to their high specific capacity. However, the low rate capability of these electrodes, still considered "battery-type" electrodes, presents an obstacle for general use. In this work, we demonstrate a successful and fast fabrication process of metal sulfide-carbon nanostructures ideal for charge-storage electrodes with ultra-high capacity and outstanding rate capability. The novel hybrid binder-free electrode material consists of a vertically aligned carbon nanotube (VCN), terminated by a nanosized single-crystal metallic Ni grain; Ni is covered by a nickel nitride (Ni3N) interlayer and topped by trinickel disulfide (Ni3S2, heazlewoodite). Thus, the electrode is formed by a Ni3S2/Ni3N/Ni@NVCN architecture with a unique broccoli-like morphology. Electrochemical measurements show that these hybrid binder-free electrodes exhibit one of the best electrochemical performances compared to the other reported Ni3S2-based electrodes, evidencing an ultra-high specific capacity (856.3 C g-1 at 3 A g-1), outstanding rate capability (77.2% retention at 13 A g-1), and excellent cycling stability (83% retention after 4000 cycles at 13 A g-1). The remarkable electrochemical performance of the binder-free Ni3S2/Ni3N/Ni@NVCN electrodes is a significant step forward, improving rate capability and capacity for redox-based supercapacitor applications.
RESUMO
O presente relatório teve como objectivos, reflectir sobre processo de aquisição de competências do enfermeiro especialista em enfermagem de reabilitação e analisar a efectividade dos cuidados de enfermagem de reabilitação no domicílio á pessoa em situação de AVC, recorrendo ás etapas da prática baseada na evidência e mobilizando a metodologia PI[C]O. A análise dos artigos seleccionados para a revisão sistemática da literatura, evidencia que os cuidados de enfermagem de reabilitação no domicílio promovem ganhos de independência no auto cuidado e nas capacidades da família/cuidador em cuidar, com implicações positivas na recuperação funcional e social da pessoa em situação de AVC. No entanto, não aprofunda alguns aspectos relacionados com a efectividade da reabilitação domiciliária, como sejam, o seu custo-eficácia, satisfação dos clientes /cuidadores, prevenção de complicações/reinternamentos, entre outros, que importa analisar, por forma a constituir a reabilitação no domicílio á pessoa em situação de AVC uma alternativa efectiva ás unidades de reabilitação
The objective of this report was to reflect on the process of skills acquisition of the specialist nurse in rehabilitation nursing as well analyzing the effectiveness of home rehabilitation nursing care for an individual in a CVA situation, using the evidence-based practice steps and mobilizing the PI[C]O methodology. The analysis of selected articles for the systematic review of literature reveals that home nursing rehabilitation care promote independence gains in self care and in the ability of the family/caregiver to take care with positive implications on the functional and social recovery of the individual in a CVA situation. However, does not develop some aspects related to the effectiveness of home rehabilitation, such as its cost-effectiveness, customer/caregivers satisfaction, prevention of complications/rehospitalizations, among others, which must be analysed, in order to make home rehabilitation to an individual in a CVA situation an effective alternative to institutional rehabilitation units.institucionais